Telephone exchange system



June 21, 1932. R. F. MASSONNEAU I TELEPHONE EXCHANGE SYSTEM wFiled Sept.25, 1931 a o mm \b n booo INVEN-TOR REMASSONNEA U By ATTORNEY 5 TI oniii 7 w l fl i Lmn E Patented June 21, 1932 ATENT OFFICE ROBERTFgMAssonNnA or 'SCA'RSDALE, NEW YORK, AssIeNon. To innn firem n-LABORATORIES, INCORPORATED, osnnw YORK, N. .Y., A conronmxon or NEWYORK - TELEPHONE EXCHANGESYSTEM Application filed September 25, 1931.Serial No. 565,053.

charges are made automatically.

The objects are to facilitate. the establishment of connections bysubscribers on a party li'ne,to i sure the p roperassessment of servicecharges against calling parties, to render 1. it'impossible foraflcallingsubscriber to evade the service charge, and tootherwiseimprove systems of thischar'acter.

= Systems have been proposed heretofore in which-tests are made by theapplication of sources of alternating current of "different frequenciesto identify the calling station in order to enable the selection andoperation of the [corresponding message register. It has also-beensuggestedto employ alteriv 2 nating current impulses for the purpose ofcontrollingthe selective'operation of automatic switches; Moreovenfit'is old for a calling subscriber on a party line to send a special codeindividually characteristic" of his stationto effect the selectionandoperation'of his service meter. According to, the present invention,advantages are secured ,over arrangementsof the foregoing character bymeans of a party line'telephone'system in which a calling party, byfirst dialing'his own party designation," selects one of a number'ofsources of alternating current. This selected source is individual tothe calling station and may be used only by that station fordialingalternating-current impulses to cause the selective operati'on'ofthece'ntral oflice switches to complete the connection to the" calledline. These results are secured by equipping the several stations on aparty line with circuits tuned respectively to different frequencysources of alternating current so that any particular party will be ableto send switch operating impulses only if he'has first dialed the codeidentifying his station. The act of dialing the. identifying code of thecalling station infaddition to causing the selection of the propersource to enable further dialing also causes the selection and operationofthe calling subscribers message register. Should a calling partyattempt toevade the service charge by dialing the code of anotherstation, the frequency'thus 'selected will not correspondwith the tunedcircuit at his station and any further operation of his dial will an tosmbns t e desired connection. Not only will'he fail to secure'aconnection, but none of the service meters associated"with his line willbe operated.

Thedrawing shows the invention applied to a'founparty line in'anautomatic telephone'system. V v I The drawing shows, diagrammatically,four subscribers stations J M, Rand WJ'a line-finder switch LF and anassociated selec- -tor SWltCh'S,'aI1d aregister 'sender RS for recordingthe ofiice and numerical digits of a called subscribers number'and' forcontrolling the operation of the various switches used'in extending aconnection between" a calling and a called'station. 1 i 1 The telephoneequipment at each of the sub: 'scribers stations J, M, R and W is of theusual type, providedwitha dialing device for use in directing theextension ofthe'callin'g line to any other line with which a'co'nnection' is desired; the ringing equipmenthas been omitted since itis not involved in this invention. Each of these stations is alsoprovided with an alternating-current filter; the filter at station' jJcomprises the condenser 1 and coil'2 ;'the*filter at station M comprisesthe condenser 3 and coil 4; the filter at station R comprises thecondenser 5 and coil 6 and the filter at station W comprises thecondenser 7 and coil 8. Each of these filters, or networks, is connectedin series with the transmitter a'n'd interrupter contacts of the dialingdevice but is normally 0011 2, and through'the interrupter contacts 10of the dial to the lower conductor of line 11. The filter at station Jis designed to pass current of one frequency; the filter at station M isdesigned to pass current of a second frequency; the filter at station Ris designed to pass current of a third frequency; and the filter atstation W is designed to pass current of a fourth frequency.

The line 11 connects to terminals in the banks of a group ofline-finders in the central ofiice including the line-finder switch LFwhich is represented by the brushes designated 21 to 26, inclusive. Theusual line and line cut-off relays are provided but are not shown in thedrawing as they are not necessary to a clear understanding of theinvention. The message registers 13, 14, 15 and 16 are providedforseparately registering the calls originated and completed from eachof the four stations of line 11. The linefinder LF is permanentlyassociated with a first selector switch S which is representedschematically by thebrushes 27 28 and 29. The line-finder LF andselector S may be of the panel type and of substantially the sameconstruction and operation as is shown and described in the patent to O.H. Kopp No. 1,589,402, issued June 22, 1926. The linefinder selectorunit includes a sender-selector switch SS which is represented by thebrushes 41 to'46, inclusive, for extending a callin line to an idleregister sender such as RS; the patent to Stearn et al. 1,395,977 issuedNovember 1, 1921, discloses a system in whicha sender selector of therotary type is used for this purpose. The line-finder selectorunitincludes a sequence switch represented by the magnet 30 and the cams 31,32 and 33, for controlling the operating circuits of this unit. Thesequence switch may be similar to that illustrated in the aforementionedKopp and Stearn et al. patents. The line-finder selector unit alsoincludes the usual supervisory relay 35 which is operated in consequenceof the answer of the called subscriber, and the charging relays 36 and37 which control the operation ofthe calling subscribers messageregister. The control relay 39 is provided for transferring the callingline from connection with the register sender to the brushes of selectorS to establish the talking circuit.

The register sender IRS is in general of the same character as-theregister senders shown and described in the above mentioned patents toKopp and Stearn et al. The switches for recording the digits dialed bythe calling subscriber include a party-designation register in addtionto the usual office code and numerical registers. The party-designationregister. PTY is represented by the stepping magnet 97 and brushes 98and 99 together with the associated terminal banks; the ofiice code andnumerical registers are represented by the registers A and B, comprisingthe stepping magnets 100 and 200 with the banks and brushes 101 and 102and 201 and 202; the remaining register switches are omitted in theirentirety. The usual register-control switch is provided for successivelydirecting the dial impulses to the proper register switches; thiscontrol switch RC comprises the stepping magnet 94, the brushes 95 and96'and their associated terminal banks. All of the registers and theregister-control switches are of the type in which the brushes areadvanced one step by each'release of the stepping magnet.

Since alternating current is used for transmitting dial impulses theregister sender RC includes the transformer 51 which has four primarywindings 53, 54, 55 and 56 and a secondary winding 52 which inductivelycooperates with each of the primary windings to impose alternatingpotentials of four different frequencies across the calling line at thetime that the first letter or digit. is dialed. The potentials of thefour frequencies are supplied to the primary windings of the transformerby the sources 63, 64, 65 and 66 under the control of relays 73, 74, 75and 76. The first digit dialed indicates which of the stations on aparty line is the calling station; and during the dialing of this digitrelays 73, 74, 75 and 76 are all operated to simultaneously impose thefour dialing-frequency potentials on the line. During the dialing of thesubsequent digits, only that one of relays 73, 74, 75 or 76 is operatedwhich is eifective to impose the dialing-frequency potential whichcorresponds to the first digit dialed. Consequently, if acallingsubscriber falsely dials a party designation other than his own,the filter at his station will not pass the current from the potentialsource corresponding to the filter at his station, and the furtherdialing by the calling subscriber will not be registered at the centraloflice. Avacuum-tube receiver, comprising the tubes 84 and 89, isprovided for responding to the alternatingcurrent impulses created bythe operation of the dial. The vacuum tubes 84' and 89 are of the usualthree element type comprising a filament, a plate and a grid. Thebattery 85 supplies current for the filaments of both tubes. andsupplies the grid potential for tube 84, the battery 86 supplies currentfor the plate circuits of both tubes, and they battery 87 supplies thegrid potential for tube 89. The grid of tube 84 is connected throughcondenser 82 to conductor 50 which is included in the dialingcircuit ashereinafter described. Changes in the potential of conductor 50 aretransmitted to the grid of tube 84, thereby causing variations ofcurrent in the plate circuit of this tube. The plate circuit of tube 84is inductively coupled by transformer 88 to the grid of tube 89 whichacts .as an amplifier. An impulse relay 91 is connected in the platecircuit of tube 89. When the filament circuits are closed by the ECOoperation of the relay-81 upon seizure of the register sender, the platecircuit current through the winding of relay 91 is effective to operatethis relay- Each time thedia'lcircuit -isopened, the current inthe-plate'circuit'oftube-89 is reduced sufficiently to cause theu eleaseer relay91. The trains of dial 'imp'u'lses received by relay '91:a=resuccessively directed to the various registers by the-regseleotor SStothe register sender BS. The

line re'lay 81 -of the register sender operates in a circuit which maybetraced from battery through its right winding, winding of retard coil*80, conductor 50, terminal and brush42 of the sender-selector, lowerback contact of relay 39, brush 22 and terminal of line-finder LF, overthe lower conductor of line 11, through the lowest and the middle ib'ackcontacts of the dial at station J, through the transmitter, the leftreceiverswit'chcontact, the left winding of induction coil'9, back overthe upper conductor of line 1 1, terminal and brush 21 0f line-finderL'F, upper back contact of relay 39, brush 41 and "terminal ofsender-selector SS, through the secondary winding 52 of transformer 51,to ground. Relay 81 closes'a locking circuit through its left-"windingand inner'le'ft front Contact, through the secondary winding of tone'transformer 79, through the normal ter- :minal and brush 95 of theregister-control 'switch, to'ground. A dialtone is induced inthiscircuit through the windings of tone transforn1er79-as a signal tothe calling subscriber that the dial maybe effectively operated.Relay'81 also closes a circuit through its "right front contact foroperating relays 73, 74, 75 and 76; and, with "each ofyrelays 73, 7 4,75and 76 operated,the various sources :of dialing potentials63, 64,'and'66are respectivelyconnected to the primary windings5'3',f54,-55;and 56 of thetransformerfil. fRelay 81' also closes thecircuit for-energizing ithe=filaments of tubes 84 and 8'5,"therebyrendering these' tubes effective to respond to dial impulses.The-current in the plate circuit of tube 89 operates the impulse relay91, and -relay91 in turn closes a circuit for operating zrelay92.

[The calling subscriber first'dials a letter or numericaldigit whichcorresponds to the-pariticular party designation of the station. ToiIIustr'ate, at station J, the letter-J (or'digit '5 should be dialed;at station M',the letter (oridigit 6 shou'ldbe dialed; :at stationR','"the letter (fordi'git 7) should beldialed; and'at station W,; theletterW' (or digit.9 should be dialed. Since thecallfin question is fromstation J, the lettertJ (or digit 5)' is dialed to indicate to thecentral oflicea pparat-us that station J is thecallin'g station. Whenthe dial'is moved oif. normal, and :as long asthe dia'l is out of itsnormal position, the middle and upper back contacts of i the dial areopened and the front'contactsare closed; the lowest back contacts of thedial (that is, the interrupter contacts 'of'the dial)remaincloseduntilthe dialbegins its return movement. Thus, the directcurrent circuit through the right winding of relay 80 is opened at theoff-normal contacts of the dial,

8% and 89 sothat the corresponding ivariations in the currentthrough-the winding 'of relay-91 are effective to -oausethealternaterelease and reoperation of this relay.

The first release of relay.91,'upon receipt of the impulses created bythe dialing of the,

party-designation digit, closes axcircuit from ground at its backcontact,through the front contact of relay 92, windingof relay 9.3,brush 96 andtnormal'terminal, through the winding of stepping magnet 97,to battery. Relay 93 and magnet-97 both operate in this circuit. Relay.93 closes a circuit-for operating the stepping -magnet 94' of theregister-control switch; When relay 91- reoperatesat the end.

of the first impulse, magnet 97 releases there- "by advancing thebrushes .98 and 99 onestep,

that is, from their normaltoi-their first offnormal position. Thealternate release and reoperation of relay 91 in response to each of thesucceeding impulses. created by the dialing of the party-designationdigit, causes the alternate operation and release of magnet .97 thusadvancing: the brushes 9.8- and .99 "to :the fifth;;off-normal' terminalof their banks Relay-92 remains operated during thereceipt of impulsessince this'relay isslow in releasing- Relay93 is also slowiin releasingso; that it. remains operated until all of the impulses, correspondingto a; single'digit have been, received. Then'relay '93 releases-,magnet94 releases therebyadvancingathe brushes '95 and 96 of'theregistencontrol switch one step-to the first off-normal position.'

When 'brush 95 is advanced from its norma'l position, the dial tonecircuit through 'the left winding of relay 81 is opened and the circuitthrough the-right windings of relays 73, 74,75 and 76 is opened. Relays74, 75 and 76 release but relay 73 remains operated since its leftWinding is energized in a circuit which passes through the fiftholfnormal terminal and brush 98 of the partydesignation register. Thedialing-frequency potential source 63 continues to .be inductivelyimposed on the line 11 through windings 53' and 52 of transformer 51,but the dialingfrequen'cy potential sources 64,65 and 66 are no. longeroperatively associated .with the transformer. The dialing of each of theofiice code and numerical digits is now effective to repeat thecycle ofoperations described above as being responsive to the dialing of theparty-designation digit. The impulses createdby the dialing of the firstoffice code digit are directed to magnet 1'00, those created by thedialing of the second oflice code digit are directed to magnet 200, andthe succeeding trains of impulses are successively directed by theregister-control switch BC to the remaining register switches in likeman-- If the subscriber at station J has dialed any other partydesignation (or a digit other than 5) further dialing would beineffective. To illustrate, the subscriber at station J dials M (or 6)as the firstdigit, brush 98 is advanced to the sixth off-normalterminal. Since relay 74 is now held operated, while relays 73, and 76release, the dialing-fre quency potential source 64 remains opera-'tively associated with transformer 51. But

the condenser land coil 2 do not permit current of this frequency topass so -that the opening and closing ofthe interrupter con tacts of thedial'do not cause corresponding impulses to be received by relay 91.This condition would also result if either of dialing-frequencypotential sources 75 or 76 were at this time operatively associated withtransformer 51.

When the brushes of selector switch S and the other necessary switcheshave been directively advanced under the control of the register senderES to extend the connection to the desired line, the sequence switch ofselector S is advanced under the control of the register sender in theusual manner into the proper position for closing the talking pathdisconnected from the line-finder selector .unit after talking selectionis completed, the ringing of the called station being automaticallycontrolled by the penultimate selector of those used in completing theconnection; but in the system here illustrated the register senderremains connected with theline-find'er selector unit until theconnection is released by the calling subscriber. When the calledsubscriber answers, assuming that to be the case, the supervisory relay35 is operated in the usual manner as is fully described in theaforementioned patents to Kopp and Steam et al. As soon as the uppercontacts of interrupter 34 are closed, after relay 35has operated, acircuit is closed from ground through. the left springs ofsequence-switch cam 31, front contact of relay 35, uppercontacts ofinterrupter 34, through the winding of relay 36, to battery. Relay 36operates and locks through its right front contact and the front contactof relay 35, to the same ground. The interrupter 34 is designed tointerrupter 34, front contact of relay 35, to

ground at sequence-switch cam 31. Relay 37 locks through its frontcontact to ground at sequence switch cam 32 until the sequence swltchhas advanced beyond position-17. No further operation takes place untilthe calling subscriber replaces the receiver upon the receiver hook, atwhich time the sequence switch magnet 30 is energized-to advance theswitch into position 17, in which position the meter 13 of the callingstation J is operated. The circuit for operating meter 13 is traced fromground through the winding of this meter, brush 23 of line-finder LF,brush 43 of sender-selector SS, the fifth off-normal terminal and brush99 of the party-designation register, over conductor 38, through theleft front contact of relay 37, and through the upper right'and lowercontacts of sequence-switch cam 33 to battery. The register sender RS isthereafter released, the line-finder switch LF and the selector S beingrestored to normal in the usual manner.

If the call originates at station ,M, the calling subscriber dials theletter M (or digit 6) as the first digit, the party-designation registerbeing thereby advanced to the sixth offnormal position; in this caserelay 74 is held operated, after the brushes of the registercontrolswitch RC have advanced out of their normal position, to render thedialing-frequency potential source 64 continuously effective incooperation withtransformer 51 to supply dialing current which is passedby the condenser 3 and coil 4. If the call originates at station R, thecalling subscriber dials the letter-1R (ordigit ,7 aslthe first digit,the party-designation register beingi thereby ad- :vancedto the seventhofi n'ormal position in gilhlSCfiSG relay .7 5 is held operated torender the 'dialing-frequency potential source 65 continuously cfiectivein cooperation with transformer '51 to supply dialing current WihlClLlSpassed'by the condenser 5 and coil 6. :If the-call originates at stationW, the calling --l0"isubscriberdials the letter (or digit 9) as :thefirst digit, the party-designation *regis- -te'r :being thereby advancedtothe ninth olfrnormal position; in this case relay 76 is held-;operated to :render the dialing-frequency po- 1tential source 66continuously effective in ,cooperation with transformer 51 to supplydialing current which is passed bythe condenser 7-=and coil 8.

-It-is,-of courseyunderstood that the appli- ..'-2 --cation of-theinvention is not limited to the specificarrangement "disclosed. Anadvanrtageous modification of this arrangement would consist ofproviding-station designa- -tion relays in 'theiline-finder selectorunit c which'would control theoperation-of the calling-subscribersmeter. These relays could u be -operated :under control of brush 99' atthe time that the sequence switch of the sedoctor-S is advanced to thetalking position a and the register sender RS could then'bere- -leasedas soon as'talking'selectionis completed in the usual manner.

*What'is claimed is:

1. The combination in a telephonesystem 3:35 of a line having a callingdial, a plurality of sources of current each of I a dilierentcharacvteristic, automatic switches, means respon- #sive to theoperationof said dial for selecting a particular one of said sources of current,

'i i ra-nd means responsive to other operations of I said dial forsending. impulses of current sup- ':-=plied fromysaid iselected sourceto "cause the: selectiveoperation of said automatic switches.

1 -7 2 2.- The combination in a telephone system of a l-ine-havinga'number of stations thereon,

calling dialszfor-said stations, sourcesof aleternating currentof-rdifi'erent frequencies, each sourcebeing individual to a particular5 oneof said stations, automatic iselector --switches, means responsive'to the operation lofithe dial-at a callingstationfor selecting'thet'source of current individual-to said station, landvmeanscontrolled by vother opera- -tions of-said dial for sending-impulses ofcurrent 1 supplied from said selected source to eefliect .theloperationof said automatic selector switches. I p

. 3.: In a telephone system,vai line having a T5560 calling dial atasubstation thereof,-a plurality ot sourcesof current, each of adifferent electricalcharacteristic, automatic switches, -meansresponsive to an intial-operation of said dial for choosingaparticular'one of said -sources:otcurrent, aandi means responsive toswitches in response to t1on 'of'said device;

' other operations a of: said dial for transmitting impulses .su-ppliedfrom said tchosen source of current tocause the selective operation ofsaid switches, .saiddast-means-being rineffectiveto cause the operationof said' switches in case said dial in actuated" to select a source "ofcurrent otherthan: said particular source of current.

acteristic, filters one iat veach= of said stations for passingcurrentfrom a difi'erent' one of said sources, and means responsive tothe 'operation of the-dialing deviceat any oneof said stations forrendering the corresponding one of said sources effective duringvthelfurther operationof said device. v

plurality of subscribers stations, a calling device at each of saidstations,'apluralityiof sources of potential eachofadifl'erentcharacteristic, filtersr'one for each-of said stations forpassingcurrent from a different one *OfSElld sources, means for imposmgallfof "said sources of potentlahon said line, and

means responsive to the operation of the dial at any one of saidstationsforlmposing a 5. In a telephonesystem,a line serving a singleone of said sourcessoni'said line: dur-i ingthe further operation ofsaid dial.

6. Ina telephonesystem, aline serving: a plurality of subscribersstations, acallingde- 'vice ateach of said stations, filters one-foreach of said stations eachcof said filters de-- signedto pass current:of a different'characteristic, a pluralityof sourcesv ofcurrent each ofa different characteristic, i automatic switches, means responsive tothe operation of the dialing devicerat=anyfone ofsaid'sta tions forselecting a particularone "of said sources of current, and meansresponsive to other operations of saidl'dial for sending'rimpulses ofcurrent supplied fromzsaid selected sourceto causetthe operation ofsaidvauto matic switches.

7 In 'a telephone system, a line serving a plurality of subscribersstations, acalling device at each ofsaid stations, a plurality ofsources ofpotentiaheachof a difii'erent characteristicyfilters one for:each of said stations r'or passing currenthfrom'a different one of saidsources, :means' responsive to the operation of the dIa'lIIIg'dBVICQ, at'fifballillllg one of said stations :for imposinga'isingleonw #of saidsources" onresaid iline,"automatic switches, and meansefiective lonly ifsaid single source is the source corresponding to said calling stationvfor advancing said 8, In 'a'telepho'ne system, a line having a number ofsubstations thereon, fcal'lin'g' dials forsaid substations, a.plura'lityf of sonrces- "of alternating current having different frethefurther operaquencies each individual to a particular one of saidstations, tuned circuits for said substationseach circuit exclusivelytuned to the .frequency of the source individual thereto, :automaticswitches, means for connecting all of said sources to the line to enablea calling party to dial a preliminary series of impulses to select thesource of current individual to his station, meansfor disconnecting theremaining sources of current from said lme, and means responsive tosubsequent operations of said dial for sending impulses thereon,-calling dials for said substations,

a plurality of sources of current, each of a different characteristic,selector switches, registers respectivelyindividual to said substations,means responsive to'the operation of the dial at a calling substationfor selecting a particular one of said sources of current and forselecting the register individual to said substation, means responsiveto other operations of-said calling dial for sending impulses of currentsupplied from said selected sourceto' cause the operation of saidautomatic switches, and means for operating the selected register- 1O.In a telephone system, a line having a number of substations thereon,calling dials for said substations, a plurality of sources ofalternating current having, different frequencies each individual to aparticular one of said substations, automatic switches, messageregisters individual respectively to said substations, a control switch,means'respon- 'sive to a preliminary operation of a calling dialfor'operating said control; switch to select the source of currentindividual to the calling substation and forselecting the messageregister individual to said substation, means responsive, to furtheroperations of the calling dial for. operating said automatic switches bymeans of impulses furnished by said selected source of current, andmeans for actuating'the selected message register.

device at each of said stations,

11. In a telephone system, a line serving a plurality" of subscribersstations, a calling a message register for each of said stations, aplurality of sources of potential each of a difl'erent characteristic,filters one for each of said stations for passing current fromadi'fierent one of saidsources, means responsive to the operation of thedialing device at a calling one of said stations for selecting aparticular one of 'said sources of current, and means .efiectiveonly ifsaid selected sourcelis the one corresponding to the filterat saidcalling station foroperating the message register of said'calling'station. 1

12. In a telephone system, a line serving a plurality of subscribers,stations, a calling dial at each of said stations, a message registerfor each of said stations, a plurality of sources of current each of adifi'erent characteristic, filters one for each of said stations, eachof said filters comprising a condenser and an induction coil designed topass current from a different one of said sources, automaticswitches,,control means responsive to the operation of the dial at acalling oneof saidstations for selecting a particular one of saidsources of current, means responsive to other operations of said dialfor sending impulses of current supplied from said selected source tooperate said automatic switches, and'means cooperating with said controlmeans for operating the message register of said calling station. V

13. The combination in a telephone system of a line serving a pluralityof subscribers stations, a calling dial for each ofsaid sta-- tions,amessage register for each of said stations, a plurality of sources ofcurrent each of a different characteristic, filters one for each of saidstations, each of s'aidfilters designed to pass current from a differentone of said sources, automatic swltches, means responsive to theoperation of the dial at a calling one of said stations for selecting aparticular one of said sources-of current and for selecting one of saidmessage registers, means responsive to the operation of said dial forsending impulses of current supplied'from said selected source tooperate said automatic switches, and means for operating saidselected-message register. 7 I

14:. Ina telephone system, a line serving a plurality of subscribersstations, a calling dial for each of said stations, a message registerfor each of said stations, a plurality of sources of current each of adifferent characteristic, filters one at each of said stations forpassing current from a different one of said sources, means responsiveto the operation of the dial at any one of said stations for renderingthe corresponding one of said sources effective during the furtheroperation of said "dial and for selecting the corresponding one of saidmessage registers, and'means for operating the selected messageregister.

15. In a telephone system, a line serving a plurality of subscribersstations, a calling dial for each of said stations, a message registerfor each of said stations, a plurality of sources of potential each of adifferent characteristic, filters one for each of said stations- 7operation of said dial and for selecting. one of saidmessage registers.and means for operating said selected register. 16. In a telephonesystem, a line serving a plurality of subscribers stations, a callingdial for each of said stations, a message register for each of saidstations, a plurality of sources of potential each of a differentcharacteristic, filters one for each of said stations tuned to passcurrent from a different one of said sources, means for imposing all ofsaid sources of potential on said line, means responsive to theoperation of the dial at any one of said stations for imposing a singleone of said sources on said line during the further operation of saiddial and for selecting one of said message registers, automatic switchesresponsive to said further operation of said dial, and means foroperating said selected register.

17. In a telephone system, subscribers lines, each of said lines havinga plurality of stations, a calling dial for each subscribers station, amessage register individual to each of said stations, a plurality ofsources alternating current for use in transmitting dial impulses, thecurrent from each source being of a different frequency. an inductioncoil and a condenser at each of said stations tuned to pass current froma different one of said sources and a meter control switch operative inresponse to the dialing of a first digit at a calling one of saidstations for selecting the message register which corresponds to thedigit dialed and for rendering that one of said sources whichcorresponds to the digit dialed effective to thereafter supply thedialing current.

18. In a telephone system, subscribers lines, each of said lines havinga plurality of stations, a calling dial for each subscribers stations, amessage register individual to each of said stations, a plurality ofsources alternating current for use in transmitting dial impulses, thecurrent from each source being of a different frequency, an inductioncoil and a condenser at each of said stations tuned to pass current froma different one of said sources, a meter control switch operative inresponse to the dialing of a first digit at a calling one of saidstations for selecting the message register which corresponds to thedigit dialed and for rendering that one of said sources whichcorresponds to the digit dialed effective to thereafter supply thedialing current, and means for operating the selected register.

19. In a telephone system, subscribers lines, each of said lines havinga plurality of stations, a calling dial for each subscribers station, amessage register individual to each of said stations, a plurality ofsources of alternating current for use in transmitting dial impulses.the current from each source being of a different frequency,an inductioncoil and a condenser at each of said stations tuned to pass current froma different one of said sources, a meter control switch operative inresponse to the dialing of a first digit at a calling one of saidstations for selecting the message register which corresponds to thedigit dialed and for rendering that one of said sources whichcorresponds to the digit dialed effective to thereafter supply thedialing current, automatic register switches, means effective to operatesaid register switches in response to the further operation of saiddial, and means for operating the selected message register.

20. In a telephone system, subscribers lines each of said lines having aplurality of stations, a calling dial for each subscribers station, amessage register individual to each of said stations, a plurality ofsources alternating current for userin transmitting dial impulses, thecurrent from each source being of a difierent frequency, an inductioncoil and a condenser at each of said stations tuned to pass current froma differentone of said sources, a meter control switch operative inresponse to the dialing of a first digit at a calling one of saidstations for selecting one of said message registers and for renderingone of said sources efiective to supply the dialing current during thefurther operation of said dial, means efi'ective only if the source thusrendered effective corresponds to said calling station for responding tothe further operation of said dial, and means effective only if theselected message register is the register of said calling station foroperating said selected message register.

In witness whereof, I hereunto subscribe my name, this 22d day ofSeptember, 1931. ROBERT F. MASSQNNEAU.

